1. Field of the Invention
This invention relates to a panel shutter assembly for the entrance or exit of a building, a window, etc.
2. Description of the Prior Art
There is known a panel shutter assembly comprising a plurality of panels which are vertically movable to open and close automatically an opening, such as the entrance or exit of a building, or a window. The assembly has drawn attention particularly because of its excellent fireproofness.
The known panel shutter assembly is of the construction as shown by way of example in FIG. 15. It includes a pair of vertically extending and horizontally spaced apart guide rails 1 disposed along two vertical edges, respectively, of a shutter opening, i.e. the opening which is opened or closed by the shutter assembly to open or close the entrance or exit of a building, a window, etc. A panel storage box 2 is provided above the guide rails 1. The box 2 has an opening and is provided above its opening with a pair of horizontally spaced apart panel driving sprockets 3. The sprockets 3 are rotatable in either of two opposite directions by panel driving means M of which the output is transmitted to the sprockets 3 through speed reducers, etc. A pair of horizontally spaced apart chains 4 mesh with the sprockets 3, respectively, and are vertically movable along the guide rails 1, respectively.
A plurality of vertically adjoining shutter panels 5 are flexurally connected to one another by the chains 4 between the guide rails 1. Each panel 5 carries a pair of guide rollers 6 each at the upper end of one of its vertical edges. The guide rollers 6 are vertically movably engaged with the guide rails 1, respectively, and are capable of riding on a pair of panel supporting rails 7, respectively, which are situated in the upper portion of the box 2. The supporting rails 7 are downwardly inclined to some extent as they extend away from the sprockets 3.
Description will now be made of the operation of the shutter assembly as hereinabove described. The assembly is in its closed position when all the panels 5 lie between the guide rails 1. If the panel driving means M is started to withdraw the panels 5 into the box 2, the sprockets 3 are rotated in the direction of an arrow and cause the chains 4 to move up along the guide rails 1 and thereby withdraw the panels 5 into the box 2 one after another. If the guide rollers 6 carried by the uppermost panel 5 move past the sprockets 3 and ride on the supporting rails 7, the weight of the panel 5 causes the guide rollers 6 to roll down the inclined supporting rails 7 to bring the panel 5 to its retracted position in which it is suspended from the supporting rails 7. As the panels 5 are all fastened to the chains 4, they are withdrawn into the box 2 one after another and are folded when they are moved past the sprockets 3 and suspended from the supporting rails 7. The panels 5 which have been folded and suspended stay in a parallel and horizontally adjoining relation to one another.
It is possible to bring the shutter assembly to its closed position covering the shutter opening again if the panel driving means M is actuated for rotation in the opposite direction. The sprockets 3 are driven in the direction opposite that shown by the arrow and the chains 4 are, therefore, moved in the opposite direction to transfer the panels 5 from the supporting rails 7 to the guide rails 1.
The known panel shutter assembly as hereinabove described has, however, a drawback which is due to the inclination of the supporting rails 7. It is not sufficient for the box 2 to have a height h which is determined by the height of the individual panels 5 as folded, but it is necessary to add to it an increment .DELTA.h which can cover the difference in vertical position between the lowest and highest panels 5. The increase in height of the box 2 makes it necessary to lower correspondingly the ceiling of e.g. a store in the event that the box is mounted above the ceiling. It necessarily restricts the height of the opening which can be covered by the shutter panels. It may also exert an adverse effect on the outward appearance of the shutter assembly as a whole.
The increment h in height of the box 2 can be eliminated if the supporting rails 7 are horizontally disposed, as shown in FIG. 16. The horizontal arrangement of the supporting rails 7 is, however, not sufficient for ensuring the smooth withdrawal of the panels 5 into the box 2. Any leading panel 5 stops moving immediately after passing around the sprockets 3 and the panel 5 following it strikes against the leading panel 5 when moving past the sprockets 3.
The assembly shown in FIG. 16 includes an outer or upper guide plate 13 and an inner or lower guide plate 14 which are provided for holding the chains 4 therebetween to guide them for movement in the direction in which the panels 5 are to be withdrawn. The chains 4 are expected to sag as shown at 4f upon leaving the space between the outer and inner guide plates 13 and 14. If no such sagging takes place smoothly, however, the chains 4 are undesirably folded in a zigzag pattern as shown in FIG. 19. The chains 4 which have been folded without forming any sag 4f make an obstacle between every two adjoining panels and are very likely to allow only two or three panels 5 to be properly retracted.